I’ve been thinking about different approaches to measuring sustainability for some time now (for the purpose of this discussion, I’m concerned mostly with quantifying carbon emissions, though the discussion can be generalized beyond this). I’ve begun to categorize the measurement approaches I see into one of two categories: horizontal vs. vertical.
The horizontal approach is organization-centric. It measures total impact across an organization. The vertical approach is product-centric. It looks all the way up and down a product’s supply chain and measures the total impact of the product through its life cycle.
As 2013 comes rapidly to a close, it is worth noting, I think, that this was arguably the three hundredth anniversary of sustainability management, the formal discipline, as we know it. Indeed, the concept of sustainability management in commerce first appeared in 1713 in a book written by Hans Carl von Carlowitz (Sylvicultura Oeconomica, 1713), a Saxon tax accountant and mining administrator who more or less invented the practice of sustainable forestry. 
